The Judaeological argument for the existence of the devil

I know it's an unedifying question, but has anyone ever tried to construct an argument to prove the existence of the devil? I've wondered about this from time to time. Perhaps one way of proving the existence of the devil might go something like this:

(1) Let the devil be defined as intelligent evil.
(2) Most of what we call evil is random and chaotic.
(3) But a pattern of purpose or design in evil would be evidence of the devil.
(4) An observable phenomenon: In modern political thought, the extreme Right and the extreme Left tend to converge on one common point: anti-Semitism.
(5) The arrival of antithetical systems of thought at exactly the same destination – a quite precise form of hatred – is evidence of purpose, or design.
(6) Therefore the devil exists.

OK, I know it's not exactly an iron-clad proof. But there's my rough sketch of the Judaeological Argument for the Existence of the Devil.